Variable amplitude vibrator, for example for the manufacture of moulded concrete products

ABSTRACT

A vibrator, e.g., for the manufacture of moulded concrete products, comprises a support for a mass to be vibrated, and means for vibrating the support, said means including a chamber adapted to contain a liquid through which in operation vibrations are transmitted to the support, a further chamber adapted to contain liquid under pressure and an adjustable flow restrictor connecting the first-mentioned chamber with the further chamber.

United States Patent Sironi [4 1 Aug. 1, 1972 VARIABLE AMPLITUDE VIBRATOR,

FOR EXAMPLE FOR THE MANUFACTURE OF MOULDED CONCRETE PRODUCTS Inventor: Virginio Sironi, Milan, Italy Assignee: Vibratechniques S.A., Paris, France Filed: Nov. 24, 1970 Appl. No.: 92,478

Foreign Application Priority Data Nov. 24, 1969 France ..6940324 US. Cl ..259/1, 259/DIG. 43 Int. Cl. ..B0lf 11/00 Field of Search ..259/1, 72, DIG. 43, DIG. 44

[56] References Cited UNITED STATES PATENTS 3,544,074 12/1970 Karpacheva....' ..259/DIG. 43 7 1,017,685 2/1912 Mumford ..-...259/DIG. 43 3,151,958 10/1964 Bodine ..259/DIG. 43

Primary ExarriinerRobert W. Jenkins Attorney-Woodhams, Blanchard and Flynn [5 7] ABSTRACT A vibrator, e.g., for the manufacture of moulded concrete products, comprises a support for a mass to be vibrated, and means for vibrating the support, said means including a chamber adapted to contain a liquid through which in operation vibrations are transmitted to the support, a further chamber adapted to contain liquid under pressure and an adjustable flow restrictor connecting the first-mentioned chamber with the further chamber.

7 Claims, l Drawing Figure VARIABLE AMPLITUDE VIBRATOR, FOR EXAMPLE FOR THE MANUFACTURE OF MOULDED CONCRETE PRODUCTS This invention relates to a vibrator, for example for use in the manufacture of moulded concrete products.

The invention provides a vibrator comprising a sup port for a mass to be vibrated, and means for vibrating thesupport, said means including a chamber adapted to contain a liquid through which in operation vibrations are transmitted to the support, the chamber communicating via an adjustable flow restrictor with a further chamber adapted to contain liquid under pressure.

There may be means for chamber with a gas.

There maybe means for adjustably pressurizing the further chamber.

I The first-mentioned chamber may be bounded by a flexible diaphragm which is connected to the support to transmit vibrations thereto from the liquid.

The invention will be described, merely by way of example, with reference to the accompanying drawing.

Referring to the drawing, the vibrator installation illustrated is used for vibrating a mass of concrete (not shown). It comprises a cylindrical vessel 1 having a vertical axis, the bottom 2 of which rests on a base 3 and also serves as bottom for a coaxial internal cylinder 4, in which a guide piston 5 is adapted to move. An annular chamber 6 is thus provided between the cylinder 4 and the inside walls of the vessel 1. This chamber, which in operation is entirely filled with oil, is provided at its top with a movable closure wall constituted in this embodiment by a flexible annular diaphragm 7. At its periphery this diaphragm is gripped sealingly in a groove 8 in the top edge of the vessel 1, and in its central portion it is gripped, likewise sealingly, in a groove 9 formed in a thickened portion 10 of the top of the cylinder 4.

On the top of the piston 5 there is fastened bymeans of a clamp nut 11 an annular part 12 resting on the diaphragm 7 and solid with a movable support 13 on which the material to be vibrated is placed.

, It will thus be understood that if the volume of oil contained in the chamber 6 is varied cyclically, cyclical vibrations of the diaphragm are produced, which by means of the part 12 are communicated to the support 13 and thus to the material. In the example illustrated pressurizing the further the means for cyclically introducing oil into the chamber is constituted in known manner by a piston 14 adapted to move in the cylinder 15 in communication with the chamber 6. This piston is driven in a reciprocating movement by a connecting rod 16 connected to a rotating driving pulley l7 driven rotationally by a motor 18 and a belt 19. The big end 20 of the connecting rod can be fixed to the pulley 17 at various points spaced radially apart on the latter, with the aid of a radial slot 21 provided in the pulley.

As so far described, the vibrator is capable of operating at frequencies below the audible range. Also, since the liquid in the chamber 6 is incompressible, the vibrations produced have a constant amplitude which is independent of the load placed on the support 13; this amplitude in fact depends only on the volume of liquid pushed by the piston 14 into the chamber in each cycle.

It is also useful to adjust the amplitude of vibration according to the composition of the material to be vibrated or to other treatment conditions.

Therefore, the chamber 6 is in addition in communication through a pipe 22, provided with an adjustable loss of head device or flow restrictor 23, with an oil container 24 constituting a further chamber. The top portion of said container is in communication through a pipe 25 with a compressed air cylinder 26 provided with a pressure reduction valve 27.

, During each vibration cycle a part of the liquid pushed into the chamber 6 by the piston 14 will serve to effect the displacement of the diaphragm 7 and another part of this liquid will flow into the container 24 through the pipe 22 which contains the flow restrictor 23. If by adjusting the restrictor 23, the loss of head in the pipe 22 connecting the container 24 to the chamber 6 is increased, the volume of the liquid displaced from the container to the chamber, or in the opposite direction is reduced. Since the volume of liquid displaced by the piston 14 remains constant, the amplitude of the vibrations of the diaphragm 7 is increased.

Conversely, if the restrictor 23 is adjusted to reduce the loss of head in the pipe, a larger proportion of the liquid. displaced by the piston 14 flows into the container 24 and the amplitude of the vibrations imparted to the movable diaphragm 7 and consequently to the support 13 is reduced.

Thus, it is possible to adjust the amplitude of vibration of the support 13 without having to stop the vibrator.

The position of rest of the movable wall 7 bounding the chamber also is adjustable. By position of rest we mean the position which it occupies when the piston is stopped at mid-stroke. This is particularly advantag'eous when as in this case the movable wall 7 is constituted'by a flexible diaphragm. In order that the vibrations are regular and have a suitably shaped waveform, it is desirable that the diaphragm 7 should not be deformed when in its rest position.

The rest position of the diaphragm is adjusted by adjusting the pressure of the gas in the container 24 by means of the valve 27, according to the load on the support 13.

Adjusting the pressure causes liquid to pass between the chamber 6 and the container 24 or vice versa. Adjusting the quantity of fluid in the chamber 6 raises or lowers the diaphragm 7 thus permitting it to be brought into an undeformed shape when it is in its rest position.

The vibrator is operated as follows. The motor 18 being at rest, a mass of concrete to be vibrated is placed on the movable support 13. The pressure reduction valve 27 of the cylinder is then adjusted so that when the piston 14 is at mid-stroke the diaphragm 7 will be perfectly horizontal and undeformed. When the motor 18 is started the amplitude of vibration of the support 13 is adjusted by adjusting the flow restrictor 23. If the amplitude of the vibrations is too low, it is necessary to increase the loss of head in the restrictor 23.

Conversely, if the amplitude of the vibrations is too great, it is necessary to reduce the loss of head in the vibrator 23.

Adjustment of the restrictor 23 provides accurate control of the vibrator amplitude. Choice of different ranges of amplitude is effected by preadjustment of the radius of rotation of the connecting rod big end 20 by fixing the big end at a predetermined point in the aperture 21, thereby adjusting the stroke of the piston 14.

I claim:

1. In a vibrator having support means for a mass which is to be vibrated and vibrating means interconnected to said support means for vibrating same, said vibrating means comprising:

first wall means defining a primary chamber adapted to contain a substantially incompressible fluid therein;

said first wall means including a movable wall portion defining a part of said primary chamber and adapted for engagement with the fluid in said primary chamber, said movable wall portionbeing engaged with said support means;

input means for imposing a vibration on the fluid within said primary chamber, whereby the vibrations are transmitted through the fluid to the movable wall portion and the support means;

second wall means defining a secondary chamber adapted to contain said substantially incompressible fluid therein;

means defining flow passageway providing communication between said primary and secondary chambers, whereby at least a part of the vibrations imposed on the fluid in the primary chamber are transmitted to the fluid in the secondary chamber; and

adjustable flow restricting means associated with said passageway for controlling the flow therethrough, whereby the vibrations transmitted through the fluid to the support means can be selectively varied relative to the vibrations imposed on the fluid by the input means.

2. A vibrator according to .claim 1, wherein said substantially incompressible fluid occupies only a portion of said secondary chamber, and means associated with said secondary chamber for supplying a pressurized compressible gas thereto whereby said pressurized compressible gas occupies the remainder of said secondary chamber.

3. A vibrator according to claim 2, further including adjustment means for permitting the pressure of the compressible gas as contained in said secondary chamber to be selectively varied.

4. A vibrator according to claim 1, wherein said movable wall portion comprises a flexible diaphragm.

5. A vibrator according to claim 1, wherein said input means includes a reciprocal piston member, said piston member comprising a part of the external periphery of said primary chamber, and said input means including drive means connected to said piston means for reciprocating same for causing cyclic displacement of the fluid within said primary chamber.

6. A vibrator according to claim 1, wherein said input means includes adjustment means associated therewith for permitting the reciprocating stroke of said piston member to be selectively varied.

7. A vibrator according to claim 1, wherein said flow restricting means comprises an adjustable device as sociated with said flow passageway for permitting the flow area to be selectively varied. 

1. In a vibrator having support means for a mass which is to be vibrated and vibrating means interconnected to said support means for vibrating same, said vibrating means comprising: first wall means defining a primary chamber adapted to contain a substantially incompressible fluid therein; said first wall means including a movable wall portion defining a part of said priMary chamber and adapted for engagement with the fluid in said primary chamber, said movable wall portion being engaged with said support means; input means for imposing a vibration on the fluid within said primary chamber, whereby the vibrations are transmitted through the fluid to the movable wall portion and the support means; second wall means defining a secondary chamber adapted to contain said substantially incompressible fluid therein; means defining flow passageway providing communication between said primary and secondary chambers, whereby at least a part of the vibrations imposed on the fluid in the primary chamber are transmitted to the fluid in the secondary chamber; and adjustable flow restricting means associated with said passageway for controlling the flow therethrough, whereby the vibrations transmitted through the fluid to the support means can be selectively varied relative to the vibrations imposed on the fluid by the input means.
 2. A vibrator according to claim 1, wherein said substantially incompressible fluid occupies only a portion of said secondary chamber, and means associated with said secondary chamber for supplying a pressurized compressible gas thereto whereby said pressurized compressible gas occupies the remainder of said secondary chamber.
 3. A vibrator according to claim 2, further including adjustment means for permitting the pressure of the compressible gas as contained in said secondary chamber to be selectively varied.
 4. A vibrator according to claim 1, wherein said movable wall portion comprises a flexible diaphragm.
 5. A vibrator according to claim 1, wherein said input means includes a reciprocal piston member, said piston member comprising a part of the external periphery of said primary chamber, and said input means including drive means connected to said piston means for reciprocating same for causing cyclic displacement of the fluid within said primary chamber.
 6. A vibrator according to claim 1, wherein said input means includes adjustment means associated therewith for permitting the reciprocating stroke of said piston member to be selectively varied.
 7. A vibrator according to claim 1, wherein said flow restricting means comprises an adjustable device associated with said flow passageway for permitting the flow area to be selectively varied. 